1. Field of the Invention
This invention relates generally to sluice gate assemblies of the type having a gate disc movable relative to a stationary frame. The frame borders an opening through which the flow of a liquid is either prevented or controlled by the position of the gate disc. The frame has seat facings against which seat facings on the gate disc are urged when the gate disc is seated in the closed position. The invention is directed primarily to the provision of a resilient seal member on the gate disc which is normally spaced from the frame and its seat facings when the gate disc is in other than the seated closed position, and which is deformed against the frame seat facings by a wedge-actuated seal retainer as the gate disc is seated in the closed position.
2. Description of the Prior Art
In conventional sluice gate assemblies, the stationary frame is normally provided with machined metal seat facings against which are urged cooperating machined metal seat facings on the gate disc to provide a seal between the frame and the gate disc when the latter is seated in the closed position. Usually, a wedge arrangement is employed to seat the gate disc in the closed position.
Experience has indicated that such arrangements are prone to leakage because in practice it is difficult if not impossible to insure that the opposed seat facings on the gate disc and frame always assume the desired face-to-face relationship which is essential to the maintenance of sealing integrity when the gate disc is seated in the closed position. This is due in part to normal manufacturing irregularities, as well as to the subsequent interposition of small amounts of foreign matter between the seat facings.
In an attempt at solving this problem, it has heretofore been proposed to provide resilient seals in slidable contact with either the gate disc or the outer frame. While such arrangements do aid in improving sealing integrity, other problems are created which offset any advantage gained. For example, as compared with conventional metal seat facings, resilient seals have high coefficients of friction which greatly increase frictional resistance to movement of the gate discs. This in turn places undesirably high loads on the operating stems. Resilient seal materials are also more susceptible to abrasive damage, a drawback which of course is aggravated by their high coefficients of friction.
Other prior art arrangements include toggle or eccentric means to retract resilient seals. Generally, these are undesirable because they require submerged moving parts and additional actuating mechanisms. Inflatable seals have also been tried without success due to leakage and the need for separate inflating means.